Remote sensing systems, such as radar systems used to detect the presence, position, speed and/or other characteristics of objects, are vital to both civilian and military operations. These systems utilize electromagnetic (EM) waves to detect, track and classify, for example, precipitation and natural/man-made objects. In operation, these systems typically transmit “beams” or signals toward targets, and process reflected return signals (or echoes) for target identification and characterization. Modern radar systems include phased array radar systems which utilize a plurality of selectively-controlled, parallel-processed, antenna elements making up an antenna. Referring generally to FIG. 1, SAR systems have also been developed which may utilize, for example, a single transmitting antenna element mounted to a moving platform, such as an aircraft 6. The antenna element may be used to form a single beam 8 which is transmitted in pulses, repeatedly illuminating a portion or segment of a target area 9, and receive reflected signals including amplitude and phase data corresponding to illuminated segment of the target area. As the aircraft travels relative to the target area, reflected signals from subsequent segments of the target area are obtained over a given period of time. Using this data, image processing algorithms may generate or reconstruct high-resolution images of the entire target area, electronically simulating an image which could only be obtained by a larger antenna (i.e. an antenna having a length equal to the velocity of the aircraft multiplied by the time period). As illustrated, the flight path 12 of aircraft 6 may be an oval or circular path.
Images generated by SAR systems are often used for detection and tracking of objects that may otherwise be difficult to achieve using known photographic devices that generate imagery using visible or infrared light, especially in adverse atmospheric conditions, such as cloud cover. As currently implemented, however, these SAR systems are prone to distortion in the case of moving targets, as well as an inability to discriminate slow moving objects, such humans walking within a target area. This distortion further inhibits the systems' ability to characterize the type of target detected, as well as predict future movements.
Accordingly, improved systems and methods for providing long-range target tracking, including moving target tracking, as well as improved target characterization in all environmental conditions are desired.